A Novel Sulfided Mo/C Catalyst for Direct Vapor Phase Carbonylation of Methanol at Atmospheric Pressure

The direct carbonylation of methanol, without any halide in the feed as apromoter, is presented. A series of Mo catalysts supported on activated carbon, γ-Al_2O_3 and SiO_2were prepared. The results show that the support greatly affects the Mo catalyst in the directvapor-phase carbonylation of methanol, and activated carbon is the best supports of the investigatedsupports. In addition, the relationships between adsorptions of NH_3 and CO and carbonylation ofmethanol were investigated. A novel sulfided Mo/C catalyst had high activity and selectivity for thevapor phase carbonylation of methanol to methyl acetate without the addition of a CH_3I promoter tothe feed. The reaction conditions were optimized at a reaction temperature of 573 K, a methanolconcentration of 23 mol% and a carbon monoxide space velocity of 3,000 L/(kg·h). Under theseoptimal conditions a methanol conversion of 50%, carbonylation selectivity of 80 rnol%, andspace-time yield of 8.0 mol/(kg·h) were obtained. The active phase of this novel sulfided Mo/Ccatalyst is the non-crystalline phase, and the active component is present as MoS_(2.5) on thesurface of the activated carbon.

Green synthesis and enhanced photocatalytic activity of Ce-doped TiO2 nanoparticles supported on porous glass

A facile and green method to prepare Ce-doped TiO2 nanoparticles supported on porous glass beads is reported. An ion exchange process and subsequent calcination yielded Ce-doped TiO2 nanoparticles with a mean size of 4.8±0.3 nm. The nanoparticles were dispersed on the surface of porous glass beads. The addition of Ce enhanced the visible light absorption of the TiO2 nanoparticles in the 400-500 nm spectral window. The band gap of the as-prepared catalyst was 2.80 eV. The Ce-doped TiO2 nanoparticles immobilized on porous glass beads exhibited excellent photocatalytic activity for the visible-light-degradation of methyl orange （MO） and rhodamine B （RhB）; with rate constants of 0.095 and 0.230 min^-1 ; respectively. The effects of Ce dosage; reaction duration; and initial solution pH on the conversion of MO and RhB dyes were investigated. The green synthesis and favorable photocatalytic activity makes the Ce-doped TiO2 nanoparticles immobilized on porous glass an attractive alternative for the efficient degradation of organic pollutants.

Preparation of homogeneously dispersed and highly concentrated double-walled carbon nanotubes as catalyst support

In this study, double-walled carbon nanotubes （DWCNTs） in ethylene glycol （EG） and N,N-dimethyl- formamide （DMF） media were investigated by a simple ultrasonication method. Homogeneously dispersed and highly concentrated DWCNTs are in EG （95 vol%） and DMF （5 vol%） media without the addition of surfactant. Surface structure and crystallinity of DWCNTs undergo minimal change. The highly concentrated dispersion state of DWCNTs helps in Pt loading. Pt particles prepared in the homogenous dispersion system have small sizes and are uniformly distributed. The prepared Pt catalysts display a similar electrochemical activity to catalysts pre- pared in EG system with low concentration. The results demonstrate that homogenously dispersed and highly concentrated DWCNTs can realize mass production of Pt/ DWCNT catalysts with high electrochemical activity and low cost.